정민수 Min Soo Jeoung , 박진규 Jin Kyu Park , 이남훈 Nam Hoon Lee

DOI:

Abstract

In order to investigate characteristics of landfill settlement with different composition of MSW in solid waste landfill, three lysimeters filled with bottom ash only (Lys-A), bottom ash 70%+municipal solid waste 30% (Lys-B), and municipal solid waste only (Lys-C) respectively were operated under actual meteorological conditions. Comparing with the settlement rate of (Lys-C in order to compare settlement rates following the physical properties of municipal solid waste landfilled in solid waste landfill, the settlement rate of (Lys-A and B exhibited 3.23% and 48.49% respectively. As a result of the long-term settlement prediction with the settlement models, the power creep law model exhibited too excessive prediction, and the hyperbolic model, the logarithmic function model, and the Gibson & Lo Model predicted similar results. In (Lys-A it was predicted that the largest settlement would occur in the Gibson & Lo Model, and in (Lys-B and (Lys-C it was predicted that the largest settlement would occur in the hyperbolic model. Seeing the Cα value of second compression coefficient, it appeared that the Cα -l and Cα -2 values of (Lys-A are 0.007 and 0.010 respectively, the Cα -1, Cα -2 values of(Lys-B are 0.014 and 0.127 respectively, and the Cα-1, Cα-2 values of(Lys-C are 0.087 and 0.240 respectively. Comparing with the values of lysimeter, it can be known that it is a little larger than the value of (Lys-B, Comparing the Cα values of lysimeter. it can be seen that Cα value of secondary compression coefficient increases as content of bottom ash becomes low.

Key Words

Solid waste Landfill, Lysimeter, Long-term settlement, Settle prediction, Second compression coefficient

이승희 Seung Whee Rhee , 최효현 Hyo Hyun Choi , 박현수 Hun Su Park

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Abstract

Characteristics of ceramic support manufactured by the mixture of spent foundry sand (SFS) and sewage sludge (SS) in the pilot plant were studied. Furan sand among SFSs and sewage sludge, which comes from a wastewater treatment facility in A city, are used to make ceramic support in the pilot plant. Characteristics of ceramic support are estimated by bulk density, porosity, compressive strength, and chemical resistance. Since there are organic materials in sewage sludge, porosity is increased but compressive strength and chemical resistance are significantly decreased with increasing the content of sewage sludge. When the content of sewage sludge is less than 10wt%, porosity is more than 40% and compressive strength is greater than 30kg/cm². With respect to additives, woody waste and waste oil in foaming ceramic support were used to improve porosity but to decline compressive strength and chemical resistance. When aluminum is used as an additive, porosity and chemical resistance are almost the same as those of commercial loess support but compressive strength is significantly increased. Hence, it may be desirable that the content of sewage sludge is less than 10% and aluminum is the optimal additive to manufacture ceramic support.

Key Words

Pilot plant, Spent foundry sand, Sewage sludge, Ceramic support, Additive

박선규 Sun Gyu Park

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Abstract

As the waste concrete is increased by demolition of reinforced concrete structure according to the plan of city reconstruction and arrangement of city environment. Recycling of waste concrete will contribute to solution of environmental problems and conserve natural aggregate. Many researches have been conducted to study the engineering properties of recycled aggregate concrete. To make use of recycled aggregate, the compressive strength of recycled aggregate concrete must bo assured. This study predicted compressive strength of recycled aggregate concrete using neural network which was applied to predict properties of engineering problems. New learning algorithms for the prediction on the strength of recycled aggregate concrete is proposed focusing on input layer components and a normalization method for input data and their validity is examined through compressive strength data of recycled concrete. In Neural Network algorithm, the main input data to be trained are the specific gravity of recycled aggregate, absorption ratios of aggregate, water/cement ratios and etc. Through this study, it was confirmed that neural network successfully predict the compressive strength of recycled aggregate concrete.

Key Words

Waste Concrete, Recycled Aggregate, Compressive Strength, Neural Network

장용철 Yong Chul Jang , 김진태 Jin Tae Kim , 이성우 Sung Woo Lee

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Abstract

In recent years more than millions of discarded electronic devices, also called electronic waste (in short e-waste), are being retired each year in Korea because of rapid technology development of the electronic industry and common replacement of the devices by consumers with newer ones. In order to more effectively recover and process the e-waste produced from the consumers and to reduce its impact on the environment, the Korean Ministry of Environment (Korean MOE) has promulgated an extended producer responsibility (EPR) regulation for a number of electronic equipment in 2003. In 2007, a new legislation, ``the Act on the Resource Recycling of Waste Electrical Electronic Equipment (WEEE) and End-of-life Vehicles`` was enacted to improve the overall environmental performance of electronic products during their life cycle. This paper discusses the estimation of generation rate and disposal practices of end-of-life electronic devices by the consumers in Daejeon Metropolitan City. The study are based on a survey of 359 consumers(local residents), a review of the available literature, and conversations with local authorities. The results show that approx. 1.05 million units of electronic wastes were retired with the highest number of mobile phones (more than 620,000 units) in the City as of 2009. In 2015, about 1.3 million units of the devices are expected to be retired. The results of the survey indicate that the average replacement periods ranged from 2.3 year for mobile phone to 7.8 year for refrigerator and washing machine. The principal interest regarding e-waste is the recovery of the precious metals such as iron, copper, aluminum, and cobalt. Gold, silver, and palladium are also of economic interest. Upon recycling, economic values of e-waste retired and generated by the city in 2009 are estimated to be 30.2 billion won and 14.1 billion won, respectively. Local governments, consumers, retailers, and producers related to e-waste recycling should consider more collective actions that can be taken to promote successful collection and recycling schemes with a perspective of economic reason and resource recovery.

Key Words

Electronic waste, Recycling, Urban mining, Waste electrical electronic equipment, WEEE, Material flow analysis

김선웅 Seon Ung Kim , 김태형 Tae Hyeong Kim , 이윤희 Yun Hee Lee , 황선진 Sun Jin Hwang

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Abstract

Utilization characteristics of substrates such as glucose, mannose, galactose during ethanol production were examined using yeast (Saccharomyces cerevisiae) acclimated in each substrate. Utilization rate of the substrates was the highest in glucose and followed by mannose and galactose. The maximum ethanol production was 6 g/L from glucose medium, and the corresponding yield was 0.3 g-ethanol/g-glucose. Galactose has a relatively long fermentation time compared to other substrate, while the final production yield was indifferent. In addition, even though the ethanol production was increased by the increased glucose concentration (10. 20. 40. 80. 120 g/L of glucose), the ethanol yield was also indifferent as 0.3 g-ethanol/g-glucose.

Key Words

Bio-ethanol, Fermentation, Saccharides, Saccharomyces cerevisiae

이채영 Chae Young Lee , 이세욱 Se Wook Lee , 김상현 Sang Hyoun Kim

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Abstract

This study was designed to evaluate hydrogen production from food waste generated from the apartment houses installed with food waste disposal system. Food waste was generated at a rate of 61.4 g VS/capita/d. The hydrogen yield of food waste sampled at peak times of morning, lunch, and dinner were 35.9, 28.3, and 31.1 mL/g VSadded, respectely. Heat-treatment of food waste increased the hydrogen production by 37-46%. When food waste was collected continuously, thickened by gravity, and heat-treated, the hydrogen yield was 64.3 mL/g VS(added), 3.95 L/capita/d of hydrogen would be produced from food waste when food waste disposals were installed.

Key Words

Anaerobic, Batch fermentation, Disposal, Food waste, Hydrogen

이지현 Ji Hyeon Lee , 이우근 Woo Keun Lee

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Abstract

Geopolymer possesses excellent mechanical properties, such as fire resistance and chemical resistance. Geopolymer technology can be used to enhance the recyclability of municipal solid waste incinerator (below MSWI) ash. Alkaline activator is necessary to synthesize geopolymeric material as alumino-silicate source, forming a gel binder phase. Because its structure has the polymeric Si-O-Al framework (sialate), with SiO4 and AlO4 tetrahedral linked alternatively by sharing all the oxygen atoms. Geopolymerization process is composed of dissolution, migration and polymerization of Al and Si precursor species. MSWI ash contains various hazardous elements such as easily leachable heavy metal, soluble salts and organic compounds. These components affect the physical property of geopolymer, if MSWI ash is used as raw material. In this work, we discuss the effect of metal compounds leached out from MSWI ash particles after mixing with alkaline solution on the physical property of it. These results are thought to enhance these results enhance the recyclability of waste material, such as MSWI ash.

Key Words

MSWI, Municipal Solid Waste Incinerator, ash, Geopolymer, Dissolution, Chemical composition, Metal ion

최연석 Yeon Seok Choi , 최항석 Hang Seok Choi , 김석준 Seock Joon Kim , 김영재 Young Jae Kim

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Abstract

In Japan an explosion accident at pellet RDF (Refuse Derived Fuel) silo happened causing serious damage to surroundings a few years ago. When a RDF pile was stored for a long-time, a spontaneous combustion and a subsequent explosion phenomena were reported. In this study the property change of pellet RDF that was made of municipal solid waste and stored for a long time in storage silo was investigated for one year in order to understand the reason of explosion and to find how to prevent the accident. We measured silo temperature and concentration of H2, CH4, CO2 and CO gases from silo body and top. Concentrations of CO2 and H2, which indicate the fermentation reaction of organic compounds inside municipal solid waste, were increased by the increase of temperature inside silo that was affected by atmospheric temperature. Especially CO2 concentration was found to be a good correlation with temperature change that was caused by fermentation of organics. It is recommended for RDF silo safety that temperature and CO2, concentration should be kept under 40℃ and 1% inside silo, respectively.

Key Words

MSW RDF, Long-term storage, Spontaneous combustion, Fermentation, Silo

엄동식 Dong Sik Eom , 장주현 Joo Hyun Jang , 안종화 Johng Hwa Ahn

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Abstract

This study was carried out for sewage sludges in 30 municipal wastewater treatment plants in Gangwon-do to investigate characteristics of dewatered sludge. The proximate analysis for the sludges included 82.3 ± 3.5% for moisture and 69.4 ± 7.5% for volatile matter as dry basis. The ultimate analysis of the sludges determined the order of C>O>N>H>S. The average carbon-to- nitrogen ratio in all sludge samples was 6.4 ± 0.2. The average calorific value for the sludges was 3,880 ± 470 kcal/kg as a dry basis. The average concentrations of the heavy metals for the sludges were in order of Zn>Cu>Cr>Pb>Ni>Cr>Cd>As>Hg.

Key Words

Calorific value, Heavy metal, Proximate analysis, Sludge characteristics, Ultimate analysis

김낙주 Nack Joo Kim , 박성범 Seong Bum Park , 성현제 Hyun Je Sung , 심동민 Dong Min Shim , 장호명 Ho Myung Chung

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Abstract

This research was mainly focused on a evaluation about a performance of biogas liquefaction plant for producing liquefied bio-methane. A Biogas liquefaction plant is consisted of a biogas purification process and methane liquefaction process. This plant is located in S landfill site. We received biogas from anaerobic digestion facility in S landfill site. Biogas composition are 66% CH4, 33.75% CO2 and 1,743 ppm H2S. As operation results of biogas liquefaction plant, we effectively removed the H2S, moisture and CO2 in raw biogas by biogas purification process. Bio-methane was cooled and liquefied to cryogenic temperature (-138.9℃) by using a refrigerant nitrogen in heat exchanger. This plant was producing the amount of 4.046 L/day as liquefied bio-methane using 2.07 kW Energy/Nm3 CH4. This plant was effectively producing high quality liquefied bio-methane which CH4 concentration was 99.84% and heating value was 39.87 MJ/m3, respectively. A liquefied bio-methane has higher feasibility as a fuel of vehicle due to a high methane concentration and a high heating value.

Key Words

Biogas, Biomethane, Liquefied Biomethane, Cryogenic, Biogas purification

이원태 Won Tae Lee , 김영석 Yong Suk Kim

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Abstract

We investigated characteristics of solid wastes which were illegally dumped in the riversides of Nakdong river, South Korea, and also assessed the contamination of soil and groundwater by the wastes. Based upon the Korean Toxicity Characteristic Leaching Procedure, no hazardous waste was found in the study area. The solid wastes were classified into two categories: 1) general industrial wastes and 2) construction wastes. Select sites were further investigated to determine whether surrounding environment has been contaminated by the wastes. Soil and groundwater samples were analyzed to determine if they meet the Korea Ministry of Environment`s regulations for soil and groundwater, respectively. No significant contamination was found although nitrate level of one site was over the national standard. This was possibly due to previous agricultural activities on the site, not by the wastes.

Key Words

Solid wastes, Industrial wastes, Soil, Groundwater, Contamination

이봉춘 Bong Chun Lee , 최영준 Young Jun Choi , 정상화 Sang Hwa Jung , 최영철 Young Cheol Choi , 김주형 Joo Hyung Kim

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Abstract

Recently, researches on the possible utilization of coal ash (pond ash) on the construction materials or the building structures have been implemented, yet the results are not satisfactory. Also, composit slag for roadbed material can be recycled. However, the reduction of lump blast furnace slag need to alternative material such as sand. This study evaluated the suitability of blended aggregate as sub-base materials. For the evaluation of mechanical properties, following tests were conducted on both blended aggregate; sieve Analysis, liquid limit, plasticity index, sand equivalent test, abrasion test, compact test and CBR. As a result, it was conclued that the blended Aggregate was the material good enough to use for subbase material, and 40% or lower substitution ratio was an appropriate percentage of blended aggregates replacement for road construction.

Key Words

Blended Aggregate, Sub-base, Pond Ash, CBR

김정훈 Jeong Hun Kim , Deepak Pudasainee , 손승욱 Seung Uk Son , 윤영식 Young Sik Yoon , 서용칠 Yong Chil Seo

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Abstract

In Korea, mercury emission into the atmosphere from combustion facilities has not been strictly controlled however the emission limit is getting more stringent to meet the international trend. In the year 2010, the emission regulation were revised and the compliance of amendment on mercury emission should have evaluated. In this paper mercury emission and removal characteristics in industrial wastes incinerators (IWIs), hospital waste incinerators (HWls). cement kilns (CKs), were investigated and the measured data were examined wether they can safely meet the new emission limit value or not. Mercury speciations in flue gas at the inlet and outlet of each air pollution control devices were measured and analyzed by US EPA Method 101A and Ontario Hydro Method. Mercury emission concentrations at stack, in an average, were 139.9 μg/Sm3, 87.7 μg/Sm3 and 18.2 μg/Sm3 in IWIs, HWIs and CKs, respectively. Mercury removal in APCDs in an average were 57.7% in IWIs, 81.6% in MWIs, 57.3% in CKs. The ratio of emission concentration to regulatory emission limit (EC/EL) in an average was higher (140%) in IWIs. This implies that facilities need additional management requirements to meet the new emission limit value. The EC/EL in CKs were 18%, implies that CKs can easily meet the new mercury regulation. However, more effective management efforts are required to control mercury pollution with applicability of control technologies and to cope with the international treaty on mercury under preparation by 2013.

Key Words

Thermal treatment, Hazardous waste, Mercury emission

이경호 Kyeong Ho Lee , 최종인 Jong In Choi , 유경선 Kyung Seun Yoo

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Abstract

Sudokwon landfill has installed manifold stations to collect LFG For the effective collection of LFG it is essential to understand the functions of manifold station containing manifold and branches and the changes of flow and pressure in manifold station. We monitored the changes of pressures, velocities and gas compositions of each branch by changing the opening of butterfly valves which is currently being used to control the volume. The LFG, collected through manifold station contains various ranges of air inflow in which oxygen is consumed to oxidate methane which increase the ratio of carbon dioxide to methane in LFG Each branch combined into manifold showed different pressures, velocities and gas compositions caused by the amount of LFG collected and the degree of air intrusion. Results showed that shortage of LFG caused the increase of suction pressure in branch.

Key Words

Sudokwon Landfill site, LFG, Manifold station, Gas collection